This invention relates generally to mattress foundation structures and more particularly to a box spring assembly of a type which utilizes non-coil springs. Box spring assemblies of this general type have been known since 1964, the first such spring assembly being disclosed in U.S. Pat. No. 3,286,281. Subsequently issued patents disclosing the same general type of box spring assembly are: U.S. Pat. Nos. 3,487,480; 3,506,987; 3,574,240; 3,574,241; 3,665,529; 3,680,157; 3,755,833; 3,824,639; and 3,852,838. Box spring assemblies of the general type shown in the above list of patents, all of which are assigned to the assignee of this application, are advantageous with respect to the conventional box spring assemblies using coil springs because they provide a desired stiffer foundation for the mattress and contain a reduced amount of wire. These box spring assemblies are also advantageous from the standpoints of prolonged service life, ease of assembly and cost of manufacture.
The present invention provides a box spring assembly which utilizes a different spring from the formed wire springs utilized in the patented box spring assemblies discussed above. The spring in the present box spring assembly is a stiffer spring than springs heretofore used, this increased stiffness being an inherent feature of the spring achieved by virtue of the spring configuration. Furthermore, this increased stiffness is achieved in a spring of reduced height relative to the springs heretofore used, thereby enabling the construction of the box spring assembly with even less wire than the wire required in the box spring assemblies shown in the above patents.
It is an object of this invention, therefore, to provide an improved box spring assembly having increased resistance to load and requiring a decreased amount of wire relative to prior art structures.